Association of Bats with Histoplasmosis

Abstract

T WO YEARS ago, a family moved into an old frame dwelling in a rural neighborhood near Clarksburg, Md. Shortly thereafter several members of the family became ill with histoplasmosis. The number of bats living in the attic of the house, the quantity of bat guano in the attic and on the ground adjacent to the foundation walls, and the isolation of Histoplacsmya repeatedly from all four sides of the house out to a distance of 5 feet suggested the source from which one fatal and several clinical illnesses in the family were acquired. A clinical report of this outbreak will be made separately. The environmental conditions associated with this family epidemic may be significant in explaining the epidemiology of certain cases of histoplasmosis occurring in rural families. They may be especially significant in explaining the puzzling distribution of histoplasmin sensitivity and cases of histoplasmosis in certain towns and cities where there is no known association with chickens and where saprophytic sources of Histoplasma have not yet been detected. The saprophytic growth of Histoplasma in soil is so frequently associated with chicken excreta that it receives the immediate attention of the epidemiologist confronted by a case of histoplasmosis. The patient is questioned carefully concerning the presence of chickens in his environment and the extent of his exposure to them. Any episode involving removal of litter and exereta from a chicken house, or its use as a fertilizer on garden or lawn, is at once assumed to have provided the effective exposure. Laboratory isolation of Histopla-sma from the material under suspicion often strengthens this assumption. However, a preoccupation with the patient's exposure to chicken excreta may lead to oversight of other associations which can be equally important but which have not received general recognition. Zeidberg and associates (1) first called attention to the association between chickens and the saprophytic growth of Histoplarsma in soil fertilized by their exereta. The first isolation of Histopla7sma from soil was from a specimen collected under a chickenhouse, although the building was not identified in the report (2). This association has been widely recognized and confirmed by many investigators. Many isolations of Histo plasma from sites not associated with chickens have been reported, however. These include the earthen floor of a meathouse, miscellaneous farm buildings and a dog pen (3,4), an old unused silo (5, 6), river water (7), a storm cellar, an old water tower, an old chalk mine, soil under a residence, low moist woodland, an abandoned schoolhouse (8,9), and a hollow tree trunk (8-10). One recognized association has been with caves known to be sources of infection for speleologists, casual visitors, or persons working in caves in the mining of guano or collection of other materials. In 1948, Washburn, Tuohy, and Davis (11) reported pneumonitis occurring in persons entering a cave. It is not reported whether bats were present. They called this disease cave sickness and suggested that it was a new disease entity. The patients did not reDr. Emmons is with the Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, Public Health Service. W. R. Piggott, W. Mitchell, and W. B. Hill, Jr., also with this laboratory, provided technical assistance.